Merge pull request rails#9969 from divineforest/fix-find-in-batches

Fail early with "Primary key not included in the custom select clause" i...

activerecord/CHANGELOG.md

@@ -1,3 +1,11 @@
+*   Fail early with "Primary key not included in the custom select clause"
+    in find_in_batches.
+
+    Before this patch find_in_batches raises this error only on second iteration.
+    So you will know about the problem only when you get the batch size threshold.
+
+    *Alexander Balashov*
+
 *   Ensure `second` through `fifth` methods act like the `first` finder.
 
     The famous ordinal Array instance methods defined in ActiveSupport

activerecord/lib/active_record/relation/batches.rb

@@ -102,16 +102,13 @@ def find_in_batches(options = {})
       while records.any?
         records_size = records.size
         primary_key_offset = records.last.id
+        raise "Primary key not included in the custom select clause" unless primary_key_offset
 
         yield records
 
         break if records_size < batch_size
 
-        if primary_key_offset
-          records = relation.where(table[primary_key].gt(primary_key_offset)).to_a
-        else
-          raise "Primary key not included in the custom select clause"
-        end
+        records = relation.where(table[primary_key].gt(primary_key_offset)).to_a
       end
     end
 

activerecord/test/cases/batches_test.rb

@@ -46,7 +46,9 @@ def test_each_enumerator_should_execute_one_query_per_batch
 
   def test_each_should_raise_if_select_is_set_without_id
     assert_raise(RuntimeError) do
-      Post.select(:title).find_each(:batch_size => 1) { |post| post }
+      Post.select(:title).find_each(batch_size: 1) { |post|
+        flunk "should not call this block"
+      }
     end
   end